1. Field of the Invention
The present invention generally relates to a process for scouring and bleaching textile materials and to a process for reducing foam in an aqueous alkyl polyglycoside composition.
2. Statement of the Related Art
Textile materials are among the most ubiquitous in society. They provide shelter and protection from the environment in the form of apparel, and comfort and decoration in the form of household textiles, such as sheets, upholstery, carpeting, drapery and wall covering, and they have a variety of industrial functions, such as tire reinforcement, tenting, filter media, conveyor belts, insulation, etc.
Textile materials are produced from fibers (finite lengths) and filaments (continuous lengths) by a variety of processes to form woven, knitted and nonwoven (felt-like) fabrics. In the case of woven and knitted fabrics, the fibers and filaments are formed into intermediate continuous-length structures known as yarns, which are interlaced by weaving or interlooped by knitting into planar-flexible sheetlike structures known as fabrics. Nonwoven fabrics are formed directly from fibers and filaments by chemically or physically bonding or interlocking fibers that have been arranged in a planar configuration.
Textile fibers are classified into two main categories, man-made and natural. Man-made fibers are formed by extrusion processes known as melt-dry, or wet spinning. The spinning or extrusion of filaments is normally followed by an operation known as drawing. In this step, the newly formed filaments are irreversibly extended and stabilized by setting or crystallization processes.
With the exception of silk, naturally occurring fibers have finite lengths and generally require several cleaning and purification steps prior to processing into yarns and fabrics.
There are a number of finishing process as that textile fibers are subjected to after their formation. The two with which the present invention is mostly concerned are scouring and bleaching. Scouring refers to the removal of sizing materials, lubricants and other impurities which are contained in and/or adhere to the fibers during their formation. These various impurities must be removed so that the textile fibers may be further processed. Another finishing process is bleaching whereby a white color is imparted to the fabric. This bleaching step also enhances the absorbency of the fiber materials in preparation for the application of other finishing processes as well as the removal of any residual impurities left over from the scouring process.
Both the scouring and bleaching processes are performed under extremely alkaline conditions using high concentrations of peroxide and/or caustic soda, and at high temperatures. Due to the extremely hot and alkaline environment, there is a need for a textile scouring and bleaching composition which is stable under these circumstances, while at the same time having low levels of foam formation under high agitation. Moreover, as a result of the current degree of enhanced consciousness with respect to the protection of our environment, the composition employed should be highly biodegradable as well. Thus, it is an object of this invention to provide a more effective means of scouring and bleaching textile fibers in an environmentally safe manner.
Another aspect of the present invention is reduction in the foam associated with the use of alkyl polyglycoside surfactants. It is known that alkyl polyglycosides exhibit significantly higher foaming profiles than other nonionic surfactants such as alcohol ethoxylates. In fact, it can be said that the foaming tendencies of alkyl polylgycosides more closely resemble those of anionic surfactants such as alcohol sulfates than the foaming tendencies of other nonionic surfactants. The higher foaming tendency of alkyl polyglycosides makes their use in certain types of applications disadvantageous. For example, public transportation vehicles are normally cleaned by spray washing with aqueous cleaning compositions applied from high pressure nozzles. Since such high pressure applications can produce significant amounts of foam, the surfactant used in these cleaning operations must have a minimum foaming tendency. Foaming problems can also arise when high foaming surfactants are used with floor cleaning machines. Consequently, users of alkyl polyglycosides are always looking for methods of decreasing the foaming tendency of aqueous alkyl polyglycoside compositions without simultaneously affecting the beneficial properties of the alkyl polyglycosides such as cleaning ability. It is, therefore, another object of the present invention to reduce the foaming tendency of aqueous alkyl polyglycoside compositions.